Bifurcation and Periodicity in Granular Soils: Implicationsto Geomechanics and Hazard Mitigation

该项目将为颗粒材料构建一种内部的、与长度相关的塑性理论，用于研究不稳定现象。将对这一概念进行分析、数值和实验评估，以确定该方法提供有关相关变形不均匀的生长和波长选择的信息的能力。内部长度标度将通过表征应力不对称性的Cosserat型修正或表征塑性流动规则的非均质性的梯度相关项来引入。我们将研究这两种方法的优缺点，并将使用最简单的形式来研究三类与危险有关的问题：剪切带、表面不稳定性和液化。这项工作将提供对物理故障过程的更好了解，这些过程对于制定适当的缓解措施至关重要。

The project will construct an internal, length-dependent plastic theory for granular materials to be applied to the study of instability phenomena. Analytical, numerical and experimental evaluation of this concept will be conducted to determine the ability of this approach to provide information on the growth and wave length selection of the associated deformation inhomogeneities. The internal length scale will be introduced either through a Cosserat- type modification characterizing the assymetry of stress, or a gradient-dependent term characterizing the heterogeneity of the plastic flow-rule. The merits and drawbacks of both approaches will be examined and the simplest possible form will be used to study three classes of hazard-related problems: shear banding, surface instabilities, and liquefaction. This work will provide a better understanding of the physical failure processes which are fundamental for the development of appropriate mitigation measures.